KR101945878B1 - Polishing pad comprising window having similar hardness with polishing layer - Google Patents

Abstract

Embodiments relate to a polishing pad comprising a window having a hardness similar to that of the polishing layer, wherein the polishing pad comprises a window having hardness and polishing rate similar to that of the polishing layer, such as a scratch of the wafer, . ≪ / RTI > In addition, the polishing layer and the window of the polishing pad are similar in hardness change rate with temperature, so that a similar hardness can be maintained even by the changed temperature during the CMP process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a polishing pad having a hardness similar to that of a polishing layer,

Embodiments relate to a polishing pad comprising a window having a hardness similar to that of the polishing layer, wherein the polishing pad comprises a window having hardness and polishing rate similar to that of the polishing layer to prevent scratching of the wafer during the CMP process .

The CMP polishing pad is an essential material that plays an important role in the chemical mechanical planarization (CMP) process during the semiconductor manufacturing process, and plays an important role in implementing the CMP performance. The CMP process is a process for planarizing the surface to be bonded of a semiconductor wafer to facilitate the subsequent machining. Many endpoint detection techniques have been proposed to determine when a semiconductor wafer has been polished to a desired degree in such a CMP process. For example, a technique has been proposed in which a semiconductor wafer is optically inspected to determine a polishing end point. The optical inspection can be performed by forming a transparent window on the polishing pad, which can detect polishing conditions, etc., and using an optical signal such as a laser through the window. In the planarization process, The end point is detected through the reflectance which is changed when the reflectance is changed.

Unlike the abrasive layer, the window is generally transparent without any microstructure and pattern because it has a high transmittance when compared to an abrasive layer (refer to Korean Patent No. 10-0707959). However, due to the structural characteristics of such a window, differences in physical properties such as polishing rate and hardness of the polishing layer and the window occur during the CMP process, which may cause surface defects such as scratches on the wafer during the CMP process.

Korean Patent No. 10-0707959

Accordingly, it is an object of the embodiments to provide a polishing pad capable of preventing surface defects such as scratches on a semiconductor wafer during a CMP process, including a window having a hardness and a polishing rate similar to those of the polishing layer.

In order to achieve the above object,

A polishing layer having a through hole formed therein; And

And a window inserted into the through hole,

Wherein the wet hardness difference between the window and the abrasive layer is between about 0.1 and about 12 Shore D,

At this time, the wet hardness is the surface hardness measured after immersing in water for 30 minutes.

The polishing pad according to the embodiment can prevent the occurrence of surface defects such as scratches on the semiconductor wafer during the CMP process, including a window having hardness and polishing speed similar to those of the polishing layer.

In addition, the polishing layer and the window of the polishing pad according to the embodiment have a similar rate of change in hardness according to the temperature, so that similar hardness can be maintained by changing temperature during the CMP process.

Figures 1 and 2 are cross-sectional views of a polishing pad of one embodiment.

One embodiment includes a polishing layer having a through-hole formed therein; And

And a window inserted into the through hole,

Wherein the wet hardness difference between the window and the abrasive layer is between about 0.1 and about 12 Shore D,

At this time, the wet hardness is the surface hardness measured after immersing in water for 30 minutes.

Referring to FIG. 1, the polishing pad of one embodiment includes an abrasive layer 101 having a through-hole 201 formed therein; And a window (102) inserted in the through hole.

window

The window may have a wet hardness in the temperature range of 30 to 70 占 폚 of 50 to 70 Shore D. Specifically, the window may have a wet hardness in the temperature range of 30 to 70 占 폚 of 50 to 65 Shore D, 52 to 65 Shore D, or 52 to 63 Shore D.

The window may have a wet hardness at 30 占 폚 of 60 to 70 Shore D. Also, the window may have a wet hardness at 50 ° C of 56 to 68 Shore D. Further, the window may have a wet hardness at 70 DEG C of from 50 to 66 Shore D's. Specifically, the window may have a wetting hardness at 30 占 폚 of 60 to 63 Shore D, a wetting hardness at 50 占 폚 of 55 to 58 Shore D, and a wetting hardness at 70 占 폚 of 50 to 53 Shore D.

The window may have a value of 20 to 25 Shore D / 占 폚 calculated from the following Equation 1 at a temperature range of 30 to 70 占 폚. Specifically, the window may have a value of 21 to 23 Shore D / 占 폚, calculated by the following Equation 1 at a temperature range of 30 to 70 占 폚.

The window may be formed from a window composition comprising a second urethane-based prepolymer and a curing agent. The content of the unreacted isocyanate group (NCO) of the second urethane prepolymer may be 8.1 to 9.0 wt%. Specifically, the content of the unreacted isocyanate group (NCO) of the second urethane prepolymer may be 8.5 to 9.0% by weight.

The term "prepolymer" generally means a polymer having a relatively low molecular weight in which a degree of polymerization is interrupted at an intermediate stage in order to easily form a final molded product. The prepolymer can be molded on its own or after reacting with other polymerizable compounds. Specifically, the urethane-based prepolymer is prepared by reacting an isocyanate compound with a polyol, and may include an unreacted isocyanate group (NCO).

The curing agent may be at least one of an amine compound and an alcohol compound. Specifically, the curing agent may include one or more compounds selected from the group consisting of aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols. For example, the curing agent may be selected from the group consisting of 4,4'-methylenebis (2-chloroaniline) (MOCA), diethyltoluenediamine, diaminodiphenyl methane, diaminodiphenylsulphone , m-xylylene diamine, isophoronediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, polypropylenediamine, and the like. But are not limited to, polypropylenetriamine, ethyleneglycol, diethyleneglycol, dipropyleneglycol, butanediol, hexanediol, glycerine, trimethylolpropane, And bis (4-amino-3-chlorophenyl) methane).

The window may be the same size as the through hole of the abrasive layer.

Since the window is a non-foam and no microbubbles are present in the window, the possibility of the polishing liquid penetrating into the polishing pad is reduced, thereby improving the precision of optical endpoint detection and preventing damage to the light transmitting region.

The window may have a light transmittance of 20% or more, or 30% or more, for light of 400 to 700 nm.

Abrasive layer

The abrasive layer may have a wet hardness of 45 to 65 Shore D at a temperature range of 30 to 70 占 폚. Specifically, the abrasive layer may have a wet hardness of 50 to 65 Shore D, or 50 to 61 Shore D at a temperature range of 30 to 70 캜.

The abrasive layer may have a wet hardness at 30 占 폚 of 55 to 65 Shore D. Also, the abrasive layer may have a wet hardness of 50 to 60 Shore D at 50 캜. Further, the abrasive layer may have a wet hardness at 70 캜 of 45 to 55 Shore D. Specifically, the abrasive layer has a wetting hardness at 30 캜 of 55 to 61 Shore D, a wet hardness at 50 캜 of 53 to 56 Shore D, and a wet hardness at 70 캜 of 50 to 53 Shore D .

The polishing layer may have a value of 20 to 30 Shore D / 占 폚, which is calculated by the following Equation 1 at a temperature range of 30 to 70 占 폚. Specifically, the abrasive layer may have a value of 23 to 27 Shore D / 占 폚, which is calculated by the following Equation 1 at a temperature range of 30 to 70 占 폚. Further, the difference between the values calculated by the following equation (1) for the window and the polishing layer is 1 to 5 Shore D / 占 폚.

[Equation 1]

The abrasive layer may be formed from a polishing layer composition comprising a first urethane-based prepolymer, a hardener and a foaming agent. The content of the unreacted isocyanate group (NCO) of the first urethane prepolymer may be 7.5 to 9.5% by weight. Specifically, the content of the unreacted isocyanate group (NCO) of the first urethane prepolymer may be from 8.0 to 8.5% by weight.

The urethane-based prepolymer may be prepared by reacting an isocyanate compound with a polyol, and may include an unreacted isocyanate group (NCO).

The difference in content of the unreacted isocyanate groups (NCO) of the first urethane prepolymer and the second urethane prepolymer may be 0.4 to 1.0 wt%. Specifically, the difference in content of the unreacted isocyanate groups (NCO) of the first urethane prepolymer and the second urethane prepolymer may be 0.5 to 0.8 wt%.

The curing agent is as described in the above window.

The foaming agent is not particularly limited as long as it is commonly used for forming voids in the polishing pad. For example, the foaming agent may be at least one selected from the group consisting of a solid foaming agent having a void, a liquid foaming agent filled with a volatile liquid, and an inert gas.

The thickness of the abrasive layer is not particularly limited, but may be, for example, 0.8 to 5.0 mm, 1.0 to 4.0 mm, or 1.0 to 3.0 mm.

The wetting hardness difference between the window and the abrasive layer may be between 0.1 and 12 Shore D. Specifically, the wetting hardness difference between the window and the abrasive layer may be 0.1 to 10 Shore D. More specifically, the wetting hardness of the window can be from 0.1 to 10 Shore D, from 0.1 to 8 Shore D, from 0.5 to 8 Shore D, or from 1 to 5 Shore D greater than the wetting hardness of the abrasive layer.

When the wet hardness difference between the window and the polishing layer is within the above range, it is possible to prevent the surface of the wafer from being damaged during the CMP process and to prevent the polishing fluid from penetrating into the polishing pad due to the deformation of the window, .

The hardness deviation rate of the window and the abrasive layer is 0.1 to 13% at a temperature range of 30 to 70 캜, and the hardness deviation rate can be calculated by the following equation (2). Specifically, the polishing pad may have a hardness deviation rate of 0.1 to 10%, 0.5 to 10%, 1 to 8%, or 2 to 7% of the window and the abrasive layer in the temperature range of 30 to 70 캜.

When the wet hardness deviation rate of the window and the polishing layer is within the above range, the similar hardness can be maintained even by the changed temperature during the CMP process, and the occurrence of surface defects such as scratches on the wafer during the CMP process can be prevented.

The wear rate of the window may be equal to or slightly higher than the wear rate of the abrasive layer. In this case, it is possible to prevent a problem that scratches are generated on the wafer to be polished by projecting only the window portion after polishing progress for a predetermined period of time. Specifically, the wear rate of the window may be 80 to 100% of the wear rate of the abrasive layer. More specifically, the wear rate of the window may be 90 to 100% of the wear rate of the abrasive layer.

At this time, the abrasion rate was measured by using a wear tester (manufacturer: Taber, model name 174) with a load of 1,000 g, a wear wheel H-22, and a rotation of 1,000 times before and after abrasion.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[ Example ]

Example  One. Of the polishing pad  making

1-1: Preparation of Polishing Layer

PUGL-450D (product of SKC) having an unreacted NCO content of 8.0 wt% was charged in a prepolymer tank in a casting machine equipped with a urethane-based prepolymer, a hardener, an inert gas and a reaction rate controlling agent injection line, (4-amino-3-chlorophenyl) methane (product of Ishihara) was filled in the reaction vessel and Al (manufactured by Airproduct Co., Ltd.) (Ar).

The urethane-based prepolymer, the curing agent, the inert gas, and the reaction rate regulator were added to the mixing head at a constant rate through the respective injection lines, and stirred. At this time, the molar equivalent of the NCO group of the urethane prepolymer and the molar equivalent of the reactive group of the curing agent were adjusted to 1: 1, and the total charge was maintained at a rate of 10 kg / min. Further, 0.5 parts by weight of a reaction rate regulator was added to 100 parts by weight of the urethane prepolymer, and argon gas was introduced in a volume of 20% of the total volume of the urethane prepolymer. The injected raw materials were injected into a post mold (1,000 mm in width, 1,000 mm in height, 3 mm in height) and solidified to obtain a sheet-shaped abrasive layer.

Then, the abrasive layer was subjected to a surface cutting process to adjust the average thickness to 2 mm.

1-2: Manufacturing of windows

PUGL-500D (product of SKC Co., Ltd.) having an unreacted NCO content of 8.5 wt% was used as the urethane prepolymer, and the raw materials injected without injecting an inert gas when the raw materials were mixed were placed in a mold (1,000 mm width, mm), a window in the form of a cake was obtained in the same manner as in Example 1-1.

Thereafter, the cake was cut to obtain 20 sheets in the form of a sheet having an average thickness of 1.9 mm. A sheet-shaped window was prepared to produce windows of 20 mm width, 60 mm length and 1.9 mm thickness.

1-3: Support layer

A non-woven type support layer (manufacturer: PTS, product name: ND-5400H) having a thickness of 1.1 T was used.

1-4: Of the polishing pad  Produce

The abrasive layer of Example 1-1 was punched to a width of 20 mm and a length of 60 mm to form a first through hole. The support layer of Example 1-3 was punched to a width of 16 mm and a length of 56 mm, Holes were formed. Then, the support layer and the abrasive layer were thermally fused at 120 DEG C using a hot melt film (manufacturer: SKC, product name: TF-00), and a double-sided adhesive agent (manufactured by 3M, product name: 442JS) The double-sided adhesive was cut and removed by the second through hole. Thereafter, the double-sided adhesive agent was cut and removed by the second through-hole, and the window of Example 1-2 was inserted into the first through-hole and adhered to the double-sided adhesive agent to produce a polishing pad (see FIG.

Example  2.

A polishing pad was prepared in the same manner as in Example 1, except that PUGL-550D (manufactured by SKC) having an unreacted NCO content of 9.1 wt% was used as a urethane-based prepolymer in the production of a window.

Comparative Example  One.

A polishing pad was prepared in the same manner as in Example 1, except that PUGL-450D (manufactured by SKC Co.) having an unreacted NCO content of 8.0 wt% was used as a urethane-based prepolymer in the production of a window.

Test Example . Wet hardness measurement by temperature

The abrasive layer and window prepared in Examples 1 and 2 and Comparative Example 1 were cut into a size of 2 cm x 2 cm (thickness: 2 mm), immersed in water at 30 deg. C, 50 deg. C or 70 deg. C, The hardness was measured using a hardness meter (D-type hardness meter). The measurement results are shown in Table 1 below.

The hardness difference (hardness deviation) between the window and the polishing layer was calculated for each temperature from the measured wetness hardness, and the hardness deviation percentage (%) was calculated by the following equation (2) . The calculation results are shown in Table 1 below.

[Equation 1]

&Quot; (2) "

Abrasive layer window Example 1 Example 2 Comparative Example 1 Wet hardness (shore D) 30 ℃ 60.5 62.2 70.8 68.8 50 ℃ 55.7 57.3 65.9 67.8 70 ℃ 50.2 53.1 61.7 66.6 Hardness difference (shore D) 30 ℃ - 1.7 10.3 8.8 50 ℃ - 1.6 10.2 12.1 70 ℃ - 2.9 11.5 16.4 Hardness deviation rate (%) 30 ℃ - 2.81 17.02 14.5 50 ℃ - 2.87 18.31 21.7 70 ℃ - 5.78 22.91 32.67 The value calculated by Equation (1)
(shore D / C) 25.75 22.75 22.75 5.50

As shown in Table 1, the polishing pads of Examples 1 and 2 had a wet hardness difference of less than 12 Shore D between the polishing layer and the window, and in particular, the polishing pad of Example 1 had a difference in wet hardness between the polishing layer and the window of 3 Shore D was very small. On the other hand, the polishing pad of Comparative Example 1 had a wet hardness difference of the maximum of 16.4 Shore D between the polishing layer and the window, and when the CMP process was performed with the polishing pad of Comparative Example 1, surface defects such as scratches were caused on the wafer surface Lt; / RTI >

In the polishing pad of Example 1, the wet hardness deviation rate of the polishing layer and the window was remarkably small, less than 6%, but the polishing pad of Comparative Example 1 had a wet hardness deviation rate of 8% or more.

Further, the polishing pads of Examples 1 and 2 have similar values to those of Equation 1 for the polishing layer and the window. Therefore, similar hardness can be maintained by changing temperature during the CMP process, It is possible to prevent the occurrence of surface defects. On the other hand, the polishing pad of Comparative Example 1 had a difference of 20 Shore D / 占 폚 or more with respect to the polishing layer and the window calculated by Equation 1 above.

101: polishing layer 102: window
103: Adhesive layer 104: Support layer
201: through hole, first through hole 202: second through hole
203: third through hole

Claims (9)

A polishing layer having a through hole formed therein; And
And a window inserted into the through hole,
Wherein the wetting hardness difference between the window and the abrasive layer is 0.1 to 12 Shore D, wherein the wet hardness is the surface hardness measured after immersing in water for 30 minutes,
Wherein the difference in value calculated for the window and the polishing layer by the following equation 1 is 1 to 5 Shore D /
[Equation 1]

.
The method according to claim 1,
Wherein said window has a value of 20 to 25 Shore D / [deg.] C calculated in the temperature range of 30 to 70 [deg.] C by the following equation:
[Equation 1]

.
delete The method according to claim 1,
Wherein the polishing pad has a hardness deviation ratio of 0.1 to 13% in the window and the polishing layer in a temperature range of 30 to 70 캜,
Wherein the hardness deviation rate is calculated by the following equation:
&Quot; (2) "

.
The method according to claim 1,
Wherein the wetting hardness difference between the window and the abrasive layer is from 0.1 to 10 Shore D.
The method according to claim 1,
Wherein the abrasive layer has a wet hardness in a temperature range of 30 to 70 캜 of 50 to 70 Shore D,
Wherein the window has a wet hardness in the temperature range of 30 to 70 占 폚 of 45 to 65 Shore D.
The method according to claim 1,
The abrasive layer is formed from a polishing layer composition comprising a first urethane-based prepolymer, a hardener and a foaming agent,
Said window being formed from a window composition comprising a second urethane-based prepolymer and a curing agent,
Wherein the content of the unreacted isocyanate groups (NCO) in the first urethane prepolymer and the second urethane prepolymer is 0.4 to 1.0 wt%.
8. The method of claim 7,
The content of the unreacted isocyanate group (NCO) of the first urethane prepolymer is 7.5 to 9.5% by weight,
And the content of unreacted isocyanate group (NCO) of the second urethane prepolymer is 8.1 to 9.0% by weight.
The method according to claim 1,
Wherein the abrasion rate of the window is 80 to 100% of the abrasion rate of the abrasive layer.

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